Tratamento anaeróbio de esgoto doméstico seguido por filtro intermitente de areia para uso na agricultura.

Abstract

The need for sewage treatment becomes evident to the minimization of pollution loads, as well as for preservation of aquatic ecosystems, favouring its most diverse uses. For the realization of the research were developed two experimental systems with the objective of evaluating the performance of sand filters in intermittent flow regime. The experimental system 1 was composed of septic tank, consisting of three chambers with longitudinal deflectors on first Board and integrated balance tank the camera 3. After the septic tank were built two intermittent sand filters which operated in parallel with surface area of 1.94 m² each, depth of 1 m in sand filter 1 and 0, 5 m 2 filter. The filters were fed with septic tank effluent through siphon system for 5 minutes every three hours (8 cycles per day). The experimental system 2 was composed of UASB reactor, equilibrium tank and then three intermittent filters being two arranged in parallel and in series, each with sand depth of 0.5 m. System power happens through pump installed on the balance tank for influent distribution every three hours during 3 minutes for intermittent sand filters. We evaluated the physical and chemical parameters, nitrification efficiency and sanitary quality. The efficiency of nitrification filters in parallel experimental system 1 was 78% and 86%, in the filters 1 and 2, respectively, while for the 2 system, the efficiency in the filters in parallel was 51% and 52%, 62% and in the filter. The average efficiency of COD removal total in the effluent of the experimental system 1 filters was 76% and 80%. For total suspended solids removal efficiency was 70% in the filter 1 and filter 2 86%. In the experimental system 2, the efficiency of COD removal total was 53% in the filters in parallel and 59% in the filter in series. For total suspended solids removal efficiency was 44% in the filter 1, filter 2 and 34% 74% in the filter 3. The removal of phosphorus in the experimental system was 1 of 16% and 33% 1 filter in the filter 2. In the experimental system 2, the removal was 16% in 1 filter, and 50% in 2 and 3. Despite the low phosphorus removal efficiency, the effluent generated by the filters of both systems can be used in agriculture, contributing to minimize spending on industrial fertilizers. Intermittent filters, produced wastewater free of eggs of helminths in view of the recommendations of the World Health Organization for unrestricted reuse in agriculture, with regard to this parameter. The average values of termotolerantes coliforms in the effluent of the filters of two experiments presented values between 104 and 105 CFU. 100 mL-1.